Field
The disclosed and claimed concept relates generally to electrical switching equipment and, more particularly, to a switch apparatus for connection with a DC circuit.
Related Art
Numerous types of circuit interrupters are known for use in diverse applications. In certain applications, such as low power situations, the circuit interrupter can be as simple as a mechanical switch, of which many types are known.
One type of mechanical switch that is employed in somewhat higher voltage and current applications involves the use of a rotatable shaft upon which an elongated conductor is mounted. The ends of the conductor are electrically connected with a pair of contacts when the switch is in an ON condition. When the switch is moved toward its OFF condition, the shaft is rotated, which causes the elongated conductor to pivot about a pivot axis about the shaft, which causes air gaps to form between the ends of the elongated conductor and the pair of contacts as the conductor is disconnected from the contacts. While such circuit interrupters have been generally effective for their intended purposes, they have not been without limitation.
Certain applications involve DC circuits, and it has become desirable in certain applications, such as photovoltaic applications and other application, to increase the voltage and current that flow within a circuit. This increase consequently exacerbates the difficulty of extinguishing the arcs that form at the air gaps when switching a switch from an ON condition to an OFF condition. For example, it has become desirable in photovoltaic applications to increase the number of solar arrays arranged in parallel and in series, which increases current and voltage, respectively, and which must be interrupted by a circuit interrupter such as a switch. Moreover, depending upon the orientation of the contacts in relation to one another and in relation to the movable elongated conductor, it is possible that the arc created at the air gap can tend to move along the elongated conductor toward the pivot axis of the shaft. Movement of the arc toward the pivot axis of the shaft on which the elongated conductor is mounted may tend to shorten the arc and reinforce it, which is undesirable since any arc is preferably extinguished as soon as possible. While efforts have been made to employ magnets and resultant Lorentz forces to extinguish arcs in such circuit interrupters, the result has sometimes been a circuit interrupter that can only interrupt DC power of a given polarity. Moreover, magnets (such as rare earth magnets) are rather costly, and the extensive use of such magnets can undesirably increase the cost of the resultant switching device. It thus would be desirable to provide an improved circuit interrupter that provides improved performance.